Broccoli is very easy to dehydrate if you start with frozen chopped broccoli.

Spread partially thawed frozen chopped broccoli on dehydrator trays that have been lined with non-stick dehydrator sheets or parchment paper to keep the dried broccoli from falling through the holes in the mesh. Dehydrate at 130o for 6 to 10 hours or until crisp dry. Remove from trays and dry heat process in canning jars for longer shelf life.

One pound of frozen chopped broccoli yields 1 cup dried broccoli.

Partially thawed frozen chopped broccoli
Dehydrated chopped broccoli